WEST SPRINGFIELD — Entering Wednesday night’s state Division 2 semifinal, the biggest concern facing the Frontier Regional field hockey team was supposed to be Oakmont’s offense. But it was the Spartans’ defense that was the difference-maker.

The Oakmont back line held Frontier to no shots on goal and eliminated Red Hawks with a 2-0 victory at Clark Field.

This marked the second straight season the two teams met in the state semifinals. Oakmont held Frontier to one shot in a 1-0 overtime win last season. Oakmont eventually lost to Watertown in the finals. Watertown (22-0) and its 91-game winning streak will face Oakmont Saturday for the title.

It was another frustrating semifinal for the Frontier offense, even though the Red Hawks (15-5-1) did play with significantly more possession in the Oakmont zone. Despite long spurts of pressure, the Hawks never got anything through on Oakmont goalie Kayla Costa, who did not touch the ball until the final two minutes, when Frontier took a long shot that was well outside the circle and would not have counted had it gone in the net.

“They had an extremely strong defense and we had a tough time getting through them and connecting on balls,” Frontier captain Sydney Judge said. “But our defense did a great job tonight.”

While the Frontier offense struggled to break through, it did not take Oakmont long to grab the lead. The undefeated Spartans (17-0-3) controlled play early and broke through for a goal when senior midfielder Kathryn Nutting played a low, hard shot toward the net from just inside the top of the circle. The ball bounced around in front and Oakmont forward Rachel Testa finally got a stick on it, slapping it out of the crowd and off the pads of Frontier goalie Gwen Thayer for a 1-0 lead 4 minutes, 10 seconds into the game.

“You never want to start a game and shortly into it give up a goal,” Frontier coach Missy Mahar said. “I think we sat back a little on our heels after that goal. But then the girls came around, they realized there was the remainder of the first half as well as the second half to try and capitalize and come back. You can’t fault their effort. They played to the end.”

Oakmont continued to pressure in the opening 10 minutes but Thayer (eight saves) was up to the task. The goalie, who made just one save in two Western Massachusetts tournament games, kicked out a point-blank chance by Oakmont’s Sarah Morse two minutes after the goal. She then stopped a shot from Nutting at the top of the circle, then made good in the same sequence on a rebound chance from Arianna Robichaud.

“Gwen played very well for us,” Mahar said. “We talked about it going into the game. We said, ‘Gwen, remember last year. You got peppered and you kept us in the game and you had some amazing saves last year. Expect to get shot at, you’re going to get pressured today.’ But I think she composed herself well.”

Frontier turned the tides shortly after the 10-minute mark, when it earned back-to-back corners — the only two it got all game. The second corner produced a cross from Brenna Sicard, but the ball was hit high and went across the front of the net without a scoring chance.

Frontier held a slight edge in possession the rest of the half and carried it into the second. But the Red Hawks couldn’t get any shots as Oakmont regained control.

The Spartans’ first sustained chance of the half produced the game’s second goal. Oakmont earned a corner and got a shot from the top of the circle that Thayer kicked out. The Frontier defense cleared the ball but Nutting played it to the right of the net, where Tara Harrington dove head first and swatted the ball into the cage.

The Red Hawks lose three seniors — Judge, Jordan Rowe and Amy Hanas.

“I played with an amazing group of girls,” Judge said. “We had really good chemistry on the field and I think we usually play as a unit very well and I’m going to miss them.”